The present invention relates to an X-ray computed tomography (CT) system and an X-ray apparatus. More particularly, the present invention is concerned with an X-ray CT system that scans a three-dimensional region with a cone beam X-radiation, and an X-ray apparatus for the X-ray CT system.
In X-ray CT systems, a cone beam X-radiation is used to radiograph a three-dimensional region (slab) in a subject during one scan. A two-dimensional array detector detects a two-dimensional distribution of intensities exhibited by the cone beam X-radiation having passed through the slab (projection). An image is then reconstructed based on a plurality of views of projection data.
A cone beam algorithm is used to reconstruct an image. A typical cone beam algorithm is a Feldkamp algorithm (refer to, for example, Patent Document 1).
[Patent Document 1] Japanese Unexamined Patent Application Publication No. 2003-144429 (p. 4)
When any of cone beam algorithms represented by the Feldkamp algorithm is employed, a slab thickness permissible for radiography during one scan, that is, the size in a body-axis direction of a three-dimensional region is about 80 mm at maximum in practice. If the thickness is equal to or larger than 80 mm, image quality is degraded due to an increase in the number of artifacts in a reconstructed image.